Abstract
KEYWORDS:
HCCI, Diesel engine, NOx, Soot, Fuels
ABSTRACT:
The unrivalled high efficiency of Direct Injection(DI) Diesel engines makes them the preferred power source in many fields of application. Currently passenger cars equipped with Diesel engines have increased to over 43% in Europe. Recent studies show that only in the year 2003 over 50% of the new passenger cars were equipped with a compression ignition engine.
Intensive research to simultaneously reduce particulate and NOx-emissions is carried out in order to support or even expand this position under further legislative demands. The conventional exhaust gas after treatment alone seems not to be the easiest and most reliable way to undertake that.
Many manufacturers are trying to develop new combustion methods that could prevent particulate and NOx formation in the burning chamber. One of the most promising alternative, Homogeneous Charge Compression Ignition (HCCI), is presented in the paper. Experimental results for several fuels, different compression ratios, use of variable valve actuating, exhaust gas recirculation and injection strategies are presented for a production passenger vehicle engine reduced to a single cylinder. At the same time a thorough combustion analysis is carried out in order to estimate the efficiency of this method. Finally the advantages and drawbacks are highlighted together with possible future trends to expand the range of application in a production engine.